Abstract: A process for preparing ultrafine carbide powder of silicon or titanium and other carbide which are used as refractory materials comprises the steps of passing electric current to a carbon member held in contact with a material such as silicon in a vacuum vessel into which an inert gas at a desired pressure is introduced and collecting a carbide powder of the material fuming into the gas as a result of a high-temperature reaction between the material and carbon member in contact, thus producing carbide powder of ultrafine particles and of high-purity with high efficiency. A preheater facilitates the passing of electricity through the material by reducing the resistance thereof and leads to efficient preparation of the ultrafine carbide powder.